That is, love is not a rational move, since it (by a definion I'd accept) requires self-sacrifice for the good of another.
Love makes/recognizes another person's good part of your good, so, depending on the magnitude, it isn't self-sacrifice to give up some other parts of your good to increase that of your loved one's.
If love were as simple as this, that would be great.
As Ritalin said:
...it's a matter of preventing people from getting hurt. Lovesickness and heartache are, in my experience, among the worst, most devastating pains the world can offer.
"Love" requires that you risk the "devastating pain", I think. You may hold back, or engage principles that mitigate the heartache you feel when a relationship ends—to an extent this is fine, as recklessness is not good—but the risk or devastating pain is inherent in "love", as I'd define it....
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.